Surveying-instrument



(No Model.) 2 Sheets -Sheet 1.

J. HALE.

SURVEYING INSTRUMBNT. No. 313,494. Pac ented Mar. 10, 1885.

WITJVJJSSES F KOOQWM Q (No Model.) 2 sheets-she et 2.

J. HALE.

SURVEYING INSTRUMENT.

No. 313,494. Patented Mar. 10, 18.85.

uuuuuu' u WITJV'ESSES %WOW UNITED STATES PATENT FFlCEe SURVEYI-NG-INSTRUMENT.

SPECIEICATION forming part of Letters Patent No. 313,@94, da'ted M'a'ch10, 1885. Application filed October 22, 1884. (No model) To all whom, itmay conccrn:

Be it known that I, JOHN HALE, a citizen of the United States, residingat Scranton, in the county of Lackawanna and State of Pennsylvania, haveinvented certain new and us`eful Improvements in Surveying-Instruments;and I do hereby declare that the following is a full, clear, and exactdescription of the in- Vention, which will enable others skilled in theart to which it appertains to make and use the same.

This invention relates to surveying-instruments, and is speciallyadapted for usein mines or the like in lieu of the miner s compass nowcommonly employed.

The object of my invention is to provide an improved instrument of thisclass which will possess advantages in point ofsimplicity, ineX-pensiveness, and general efficiency, and which can be readily andConveniently operated.

lt is well known that the metallic or magnetic attractions which existmore or less in all coal or iron-ore mines cause a' variation of theneedle of ordinary niners compasses to such an eXtent as to render theinstrument unreliable and inaccurate.

My invention is designed to overcone all such difficulties, and toenable accurate sur- Veys and the running of true parallel lines withoutthe needle-compass, so that the metallic attraction is entirely avoided.i

In the drawngs, Figure 1 is a perspcctive View of my improvedinstrument. Fig. 2 is a vertical transverse sectional View thereof. Fig.3 is a top or plan View illustrating the operation by dotted lines. Fg.4 is a detail perspective View of the !nov-able arm.

Corresponding parts in the figures are denoted by the same letters ofreference.

Referring to the drawings, A designates the compassplate, which ispreferably semicircular, as illustrated, and provided with thegraduations a and with the sleeve or socket A by which the plate isadapted to be supported upon a tripod or staff in such a manner as to beConveniently used in mines or at any other work in which a surveyor scompass or transit is employed, a set-screw, a, being provided to securethe plate in position.

B is a movable arm, which is pivotally centered to the plate and adaptedto nove around the fixed center, the pivotal connection being formed,preferably, by apivot pin or screw, C, passing through the arm and intothe plate. At each end of the novable arm is provided a vertical sight,D, preferabl y pivoted between two lugs, b b, upon the arm by means of apivot pin or screw, d, by which arrangement the sights may be readilyfolded down when the instrument is out of use. Upon the under side ofthe movable arm, at its outer end, projects a lug, b formed with ascrewthreaded perforation, b through which works a setscrew, E, adapt-edto clamp the edge or periphery of the plate to secure the arm in theposition to which it has been adjusted. The periphery of the plate ispreferably provided with a concave groove, a, to receive the end of thisset-screw and obviate displacement or strain. Near its outer end themovable arm is preferably widened, as illustrated. and in this widenedportion is provided a transverse slot, A in which is provided a vernier,ai

The operation and advantages of myinvention will be readily understoodby those skilled in the art to which it appertains. In practice abase-line is first established in any of the known methods, such asdropping two plummets down the vertical shaft from the surface of theground. Then at the bottom of said shaft a fine copper wire is stretchedacross and extends some distance into the mines-say fifty feet, more orless-the wire being so adjusted horizontally that it will touch the twoplummet-wires above mentioned. After establishing the first base-line,my inproved instrument is placed under the mark, the movable arm beingclam'ped in position at O or zero on the scale or graduations of theplate. The base-line is well cstablished through thesights while the armis thus clanped in position,when the movable arm may be turned to theright or left at will as many degrees as desired, the second sight beingthen established, and the operation being continued to right or leftuntil the survey is completed, without fear or any liability toinaccuracy through any magnetic or metallic influences.

My improved instrument is very simple and less expensive than thetransit or the theodo- IOO lite, and it can be readily and Convenientlyoperated, and is easily understood and governed.

I claim as my invention and desire to secure by Letters Patent-- 1. In asurveying-instrument of the class deseribed, the oombination, with thegraduated compassplate, of the novable arm having its inner end pivotedcentrally in relation thereto, and vertical sights provided at thepivotail and outer ends of said arms, substantially as and for thepurpose set forth.

2. In a surveying-instrunent of the class described, the c-ombination ofthe graduated conpass-plate, the novahle arm moving around a fixedcenter in relation thereto, and provided with the vernier, and thefolding sights provided at the pivotal and outer ends of the arm,substantiallyas set forth.

3. The eonbination of the graduated conipass-plate, the movable armpivoted at its inner end thereto and moving around a fixed ceter,andprovided with the vernier and with the set-screw, and the folding sightsprovided upon the arm at its pivotal and vernier ends, substantially asset forth.

4. The combination of the graduated compass-plate provided With thegrooved edge, the movabie arni oentrally pivoted in relation thereto,and provided atits outer end with the vernier and thedownwardly-projeoting lug, the set-screw working through the latter, andthe folding sghts provided at the ends of the arm, substantially as setforth.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN HALE.

XVitn ess es:

WILLIAM GEORGE HoUsE, J AMES M.. THOMAS.

